Fine sphere, a spherical spacer for a liquid crystal display element and a liquid display element using the same

ABSTRACT

PCT No. PCT/JP91/01285 Sec. 371 Date May 28, 1992 Sec. 102(e) Date May 28, 1992 PCT Filed Sep. 27, 1991 PCT Pub. No. WO92/06402 PCT Pub. Date Apr. 16, 1992.A spherical spacer is provided for defining a gap dimension between substrates of a liquid crystal display. The K-value (hardness of a sphere) of the spherical spacer is defined as:   &lt;IMAGE&gt;   (wherein F and S represent a load value (kgf) and a compression displacement (mm) at 10% compression deformation of said fine sphere, respectively, and R represents a radius (mm) of said fine sphere) which is in the range of 250 kgf/mm2 to 700 kgf/mm2 at 20 DEG  C.; and a recovery factor after the compression deformation which is in the range of 30% to 80% at 20 DEG  C. A spherical spacer matching the newly found limitations and defining the gap between a pair of substrates into which liquid crystal is filled reduces the damage to an alignment coat when compared with spacers being too hard, and reduces quality deterioration of the image when compared with spacers being too soft.

TECHNICAL FIELD

The present invention relates to a fine sphere used as a sphericalspacer for a liquid crystal display element, a conductive fine sphereand the like. More particularly, it relates to a spherical spacer for aliquid crystal display element, a liquid crystal display element usingsame, and a conductive fine sphere.

BACKGROUND ART

FIG. 7 shows a typical liquid crystal display element of a TN (twistednematic) mode using conventional spacers.

This liquid crystal display element comprises a pair of substrates 37,39, spacers 38 disposed between the pair of substrates 37, 39 so as tomaintain a constant cell gap therebeween, a nematic liquid crystal 41, asealing material 30 filled in the periphery of the cell gap between thepair of substrates 37, 39, and polarizing sheets 42, 43 coated on thesurfaces of the respective substrates 37, 39.

The above-mentioned substrates 37, 39 are formed by patterningtransparent electrodes 32, 35 made of ITO (Indium-Tin-Oxide) films onone surface of respective transparent substrates 31, 34 made of glassand by coating the surfaces of the transparent electrodes 32, 35 and thetransparent substrates 31, 34 with alignment coat (polyimide films). Thealignment coat 33, 36 are provided with alignment control by rubbing.

The spacers 38 are made from inorganic materials including aluminumoxide, silicon dioxide and the like, or synthetic resin materialsincluding benzoguanamine, polystyrene type polymer and the like. Thespacers made from inorganic materials are disclosed, for example, inJapanese Laid-Open Paten Publication Nos. 63-73225 and 1-59974, and thespacers made from synthetic resin materials are disclosed in JapaneseLaid-Open Patent Publication Nos. 60-200228 and 1-293316.

The liquid crystal display element with the above-mentioned structure isusually produced as follows.

The spacers 38 are dispersed on the alignment coat 33 of the substrate37, and resin for sealing is coated on the periphery of the substrate 37by printing. Then, the pair of substrates 37, 39 are superimposed sothat the alignment coat 33, 36 are faced to each other and pressed. Theresin for sealing is hardened by heating to form a sealed material,thereby fixing the pair of substrates 37, 39 to each other. The nematicliquid crystal 41 is filled in the space between the pair of substrates37, 39 through a hole provided in the sealing material, and after that,the hole is closed. Then, the polarizing sheets 42, 43 are layered onthe outside surfaces of the transparent substrate 31, 34.

As spacers used for the above-mentioned liquid crystal display element,colored spherical spacers are often used for the following reasons.

In the liquid crystal display element, the liquid crystal is opticallychanged to form an image by applying a voltage between the transparentelectrodes. However, spacers are not optically changed by theapplication of a voltage. Therefore, uncolored spacers are likely to beobserved as white spots in dark portions of a displayed image, resultingin a decrease in the contrast of the image display.

Colored spherical spacers made from inorganic materials are disclosed inJapanese Laid-Open Patent Publication Nos. 62-66228, 63-89408, and63-89890. Colored spherical spacers made from synthetic resin materialsare disclosed in Japanese Laid-Open Patent Publication Nos. 1-200227,1-207719 and 2-214781.

Moreover, the spacers having no adhesion are not fixed to thetransparent substrates, giving rise to the following disadvantages.Therefore, the adhesive coated spherical spacers are often used.

1) Air blown onto or air suction from the substrates in the process ofassembling the liquid crystal display cell may cause scattering ofspacers disposed on the substrates, resulting in loss of the spacers.

2) The spacers may be displaced on the surfaces of the substrates in theprocess of injecting liquid crystal into the liquid crystal displaycell, resulting in bias of the spacer arrangement on the substrates.

3) The spacers may be displaced by the electrical or hydrodynamic forcesarising while the liquid crystal display cell is in operation.

4) The spacers may be displaced when mechanical vibration acts on theliquid crystal display cell from outside.

These displacements of the spacers in the liquid crystal display celldecrease the cell gap precision and remarkably deteriorate the imagequality.

Adhesive spherical spacers are disclosed, for example, in JapaneseLaid-Open Utility Model Publication No. 51-22453, Japanese Laid-OpenPatent Publication Nos. 63-44631, 63-94224, 63-200126, 1-247154,1-247155 and 2-251537.

However, when the spacers made from conventional inorganic materials orspacers made from the synthetic resin materials are used as spacers forthe liquid crystal display element, the following disadvantages arise.

As shown in FIG. 8, when the liquid crystal display element is producedby using the inorganic spacers 38, the spacers 38 are so hard that theydamage the alignment coat 33 when both substrates 37, 39 are pressed. Ona damaged portion 33a of the alignment coat 33, a desired moleculearrangement of the liquid crystal 41 cannot be maintained. For example,in the transmission type liquid crystal display element, the damagedportion 33a appears as a display defect.

Furthermore, the inorganic spacers 38 are hard to be deformed, so thatthe spacers 38 come into contact with the inner surfaces of thesubstrates 37, 39 at one point, respectively. As a result, the spacers38 are likely to be displaced in the space including the liquid crystal41 due to gravity or minute vibration. This disadvantage often appearsin a large liquid crystal display element used for lap-top type personalcomputers or word processors, wall-mounting TV sets, etc. which haverapidly come into wide use in recent years, since the display surface isused in the vertical direction or the inclined direction. For example,most of the spacers 38 move downward in the liquid crystal displayelement, causing nonuniformity in the thickness of the liquid crystallayer and making it difficult to provide a clear image. Also, themovement of the spacers 38 damage the alignment coat 33, causing theabove-mentioned display defect.

On the other hand, when spacers which are too soft are used, thefollowing disadvantages arise.

It is impossible to uniformly disperse the spacers 38 on the surfaces ofthe substrates 37, 39, and considerable irregularity is caused in thedispersion density. When the pair of substrates 37, 39 are pressed whilefacing each other, the pressure applied on one spacer 38 in the smalldispersion density area is large, so that the spacer 38 is largelydeformed. In contrast, the pressure applied on one spacer 38 in thelarge dispersion density area is small, so that the spacer 38 is hardlydeformed. In this way, as shown in FIG. 9, the irregularity of thedispersion density of the spacers 38 causes nonuniformity in thethickness of the liquid crystal layer disposed between the pair of thesubstrates 37, 39. As a result, a clear image cannot be obtained.

Moreover, when the pair of substrates 37, 39 are pressed, it is actuallyimpossible to apply uniform pressure onto the entire substrates 37, 39,and the substrates 37, 39 are applied with different pressures atdifferent portions thereof. Accordingly, when the spacers 38 which aretoo soft are used, the respective spacers 38 are deformed to differentdegrees because of the difference of pressure with which the spacers 38are subjected, resulting in the nonuniformity of thickness of the liquidcrystal layer. As a result, the image quality is remarkablydeteriorated.

On the other hand, in the field of electronics mounting, metal particlessuch as Au, Ag and Ni are mixed with a binder resin to prepareconductive paste, and this paste is filled between a pair of fineelectrodes, whereby the pair of fine electrodes are connected to eachother. However, such metal particles are nonuniform in shape and have alarger specific gravity compared with the binder resin, so that it isdifficult to disperse those metal particles in the binder resin.

In order to overcome those disadvantages, Japanese Laid-Open PatentPublication No. 59-28185 discloses that the surfaces of particles suchas glass beads, silica beads, and glass fibers, the particle sizes ofwhich are relatively uniform, are plated with metal to form conductivefine spheres. However, the conductive fine, spheres disclosed in theabove have core fine spheres which are too hard, and they are difficultto be deformed by compressing. Because of this, when the electrodes areconnected to each other by using the above-mentioned conductive finespheres, the contact areas between the conductive fine spheres and thesurfaces of the electrodes are not spread, making it difficult to reducecontact resistance.

Japanese Laid-Open Patent Publication Nos. 62-185749 and 1-225776discloses conductive fine spheres using polyphenylenesulfide particles,phenol resin particles and the like as core fine spheres. However, theconductive fine spheres using such synthetic resin particles as corefine spheres do not have sufficient recoverability after being deformedby compressing. Because of this, when the electrodes are connected toeach other by using these conductive fine spheres and the compressionlead acting on both electrodes is removed, non-contacting state isformed between the conductive fine spheres and the surfaces of theelectrodes, resulting in imperfect contacts.

DISCLOSURE OF INVENTION

A fine sphere of the present invention, which overcomes theabove-discussed and numerous other disadvantages and deficiencies of theprior art, has a K-value defined as K=(3/√2)·F·S^(-3/2) ·R^(-1/2)(wherein F and S represent a load value (kgf) and a compressiondisplacement (mm) at 10% compression deformation of the fine sphere,respectively, and R represents a radius (mm) of the fine sphere) in therange of 250 kgf/mm² to 700 kgf/mm² at 20° C., and has a recovery factorafter the compression deformation in the range of 30% to 80% at 20° C.

In a preferred embodiment, the K-value is in the range of 350 kgf/mm² to550 kgf/mm².

In a preferred embodiment, the recovery factor after the compressiondeformation is in the range of 40% to 70% at 20° C.

In a preferred embodiment, the fine sphere is at least one selected fromthe group consisting of polydivinylbenzene, divinylbenzene-styrenecopolymer, divinylbenzene-acrylate copolymers, and polydiallylphthalate.

In a preferred embodiment, the fine sphere is in a spherical shape, andits diameter is in the range of 0.1 to 100 μm.

In a preferred embodiment, the diameter of the fine sphere is in therange of 0.5 to 50 μm.

In a preferred embodiment, the diameter of the fine sphere is in therange of 1.0 to 20 μm.

A spherical spacer for a liquid crystal display element of the presentinvention has a K-value defined as K=(3/√2)·F·S^(-3/2) ·R^(-1/2)(wherein F and S represent a load value (kgf) and a compressiondisplacement (mm) at 10% compression deformation of spherical spacer,respectively, and R represents a radius (mm) of the spherical spacer) inthe range of 250 kgf/mm² to 700 kgf/mm² at 20° C., and has a recoveryfactor after the compression deformation in the range of 30% to 80% at20° C.

A colored spherical spacer for a liquid crystal display element of thepresent invention comprises a colored core fine sphere, having a K-valuedefined as K=(3/√2)·F·S^(-3/2) ·R^(-1/2) (wherein F and S represent aload value (kgf) and a compression displacement (mm) at 10% compressiondeformation of the colored spherical spacer, respectively, and Rrepresents a radius (mm) of the colored spherical spacer) in the rangeof 250 kgf/mm² to 700 kgf/mm² at 20° C., and a recovery factor after thecompression deformation in the range of 30% to 80% at 20° C.

An adhesive coated spherical spacer for a liquid crystal display elementof the present invention comprises a core fine sphere and an adhesivelayer formed on a surface of the core fine sphere, having a K-valuedefined as K=(3/√2)·F·S^(-3/2) ·R^(-1/2) (wherein F and S represent aload value (kgf) and a compression displacement (mm) at 10% compressiondeformation of the adhesive coated spherical spacer, respectively, and Rrepresents a radius (mm) of the adhesive coated spherical spacer) in therange of 250 kgf/mm² to 700 kgf/mm² at 20° C., and has a recovery factorafter the compression deformation in the range of 30% to 80% at 20° C.

A liquid crystal display element of the present invention is produced byusing the above-mentioned respective spherical spacers.

A conductive fine sphere of the present invention comprises theabove-mentioned fine sphere and a conductive layer formed on a surfaceof the fine sphere.

In a preferred embodiment, the conductive layer is an indium-platedlayer.

Thus, the invention described herein makes possible the objectives of:(1) providing spherical spacers which neither change the alignmentproperty of the liquid crystal by damaging the alignment coat of theliquid crystal display element nor deteriorate the image quality; (2)providing spherical spacers which do not cause irregularity in the cellgap to decrease clearness of the image (3) providing spherical spacerswhich are not displaced due to gravity and minute vibration and a liquidcrystal display element using same; (4) providing a liquid crystaldisplay element which has no image defect and provides a clear image (5)providing conductive fine spheres having appropriate compressiondeformability and recoverability from deforming and (6) providingconductive fine spheres excellent in connection reliability.

BRIEF DESCRIPTION OF THE DRAWINGS

This invention may be better understood and its numerous objects andadvantages will become apparent to those s skilled in the art byreference to the accompanying drawings as follows:

FIG. 1 is a cross-sectional view showing an example of a liquid crystaldisplay element according to the present invention.

FIG. 2 is a graph showing a relationship between the load and thecompression displacement of spacers.

FIG. 3 is a graph showing a relationship between the K-value and thecompression deformation of spacers.

FIG. 4 is a graph illustrating a method for the measurement of therecovery factor after the spacers are deformed by compressing.

FIG. 5 is a cross-sectional view showing main portions of a liquidcrystal display element produced by using conductive fine spheres.

FIG. 6 is a cross-sectional view showing a test chip (an ITO/glasselectrode for test) produced in Example 13.

FIG. 7 is a cross-sectional view showing a general liquid crystaldisplay element.

FIG. 8 is a cross-sectional view showing a liquid crystal displayelement produced by using spherical spacers which are too hard.

FIG. 9 is a cross-sectional view showing a liquid crystal displayelement produced by using spherical spacers which are too soft.

BEST MODE FOR CARRYING OUT THE INVENTION

I. Fine spheres, spherical spacers for a liquid crystal display element,colored spherical spacers for a liquid crystal display element, andadhesive coated spherical spacers for a liquid crystal display element.

Fine spheres of the present invention have a K-value in a predeterminedrange and a recovery factor after the compression deformation in apredetermined range. The fine spheres can be used as spherical spacersfor a liquid crystal display element.

Also, colored spherical spacers for a liquid crystal display elementhave a K-value in a predetermined range and a recovery factor after thecompression deformation in a predetermined range. Adhesive sphericalspacers for a liquid crystal display element have a K-value in apredetermined range and a recovery factor after the compressiondeformation in a predetermined range and exhibit adhesion when heated.

The K-value will be described.

According to The Course of Theoretical Physics by Landau-Lifshitz,"Theory of elasticity" p. 42 (published by Tokyo Tosho in 1972), whentwo elastic spheres each having radius R and R' are in contact with eachother by compression, h is given by the following equations.

    h=F.sup.2/3 [D.sup.2 (1/R+1/R')].sup.1/3                   (1)

    D=(3/4)[(1-σ.sup.2)/E+(1-σ'.sup.2)/E']         (2)

wherein h represents a difference between the distance between thecenters of both spheres and R+R', F represents compressive force, E andE' respectively represent elastic moduli of both spheres, σ, σ'represent Poisson's ratios of the elastic spheres.

On the other hand, when the spheres are placed on rigid plates andcompressed from both sides, suppose R'→∞, E>>E', the following equationis approximately obtained.

    F=(2.sup.1/2 /3)(S.sup.3/2)(E·R.sup.1/2)(1-σ.sup.2)(3)

wherein S represents an amount of compression deformation. The followingequation can be obtained by modifying the above equation (3). K-value isdefined as follows. ##EQU2## Thus, the following equation can beobtained. ##EQU3##

This K-value universally and quantitatively represents hardness of thespheres. The preferable hardness of the fine spheres or spacers(hereinafter, referred to as spacers and the like) can be quantitativelyand unequivocally represented by using this K-value.

The K-value at 10% compression deformation is in the range of 250kgf/mm² to 700 kgf/mm². When a liquid crystal display element isproduced by using the spacers and the like in this range, the spacersand the like do not damage the alignment coat. Moreover, when the gapbetween the electrodes is adjusted by pressing, the gap can be readilycontrolled. It is more preferable that the K-value at 10% compressiondeformation is in the range of 350 kgf/mm² to 550 kgf/mm².

When the spacers and the like having a K-value more than 700 kgf/mm² areused, the surfaces of the liquid crystal alignment coat are likely to bedamaged in the course of the production of the liquid crystal displayelement. Moreover, in the liquid crystal display element so produced,the spacers and the like are not likely to be changed by compression dueto the contraction of liquid crystal at decreased temperatures, wherebybabble is generated under the reduced pressure in the liquid crystalcell.

When the spacers and the like having a K-value less than 250 μkgf/mm²are used, the cell gap control becomes difficult.

The mechanical properties of the material for the preferred spacers andthe like cannot be completely shown merely by defining the preferredhardness of the spacers and the like used for the liquid crystal displayelement.

Another important condition is that the recovery factor after thecompression deformation, which is a value representing the elasticity ofthe spacers and the like, is in a predetermined range. The elasticityand plasticity of the spacers and the like can be quantitatively andunequivocally shown by defining the recovery factor after thecompression deformation.

In the spacers and the like of the present invention, the recoveryfactor of the spacers and the like after the compression deformation ispreferably in the range of 30% to 80% at 20° C. A more preferredrecovery factor is in the range of 40% to 70%.

When spacers having a recovery factor of more than 80% are used, and thegap between both substrates is adjusted by pressure pressing, followedby the reduction of pressure in the course of the production of theliquid crystal cell, the spacers and the like which are deformed bycompression are likely to return to their original shape because of theelasticity thereof, so that the cell gap of the liquid crystal cellobtained is disordered.

When the spacers having a recovery factor of less than 30% are used, andthe gap between both substrates is adjusted by pressure pressing, theportion to which excess pressure is applied is not likely to return tothe desired cell gap, since the spacers and the like remain deformed bycompression. Thus, the cell gap is disordered.

Next, the method for measuring the K-value and the recovery factor afterthe compression deformation will be described.

(A) Method for measuring the K-value and conditions thereof

(i) Method for measurement

Spacers and the like are dispersed on a steel sheet having a smoothsurface at room temperature, and one of spacers and the like is chosen.Then, the spacers and the like are compressed with a smooth end surfaceof a circular cylinder made of diamond and having a diameter of 50 μm byusing a compression test machine (PCT-200 type Shimadzu SeisekushoLtd.). At this time, the compression load is electrically detected aselectromagnetic force, and the compression displacement is electricallydetected as change by using a transformer.

The relationship between the compression displacement and the load isobtained as shown in FIG. 2. From FIG. 2, the load value and thecompression displacement at 10% compression deformation of the spacersand the like are respectively obtained. From these values and theequation (5), the relationship between the K-value and the compressiondeformation is obtained as shown in FIG. 3.

Compression distortion (%) is obtained by dividing the compressiondisplacement by a diameter of the spacers and the like.

(ii) Compression speed

The compression is performed under constant load and constant speed. Theload is increased at the rate of 0.27 g weight (grf)/sec.

(iii) Test load

The maximum load is 10 grf.

(B) Method for measuring the recovery factor after the compressiondeformation and conditions thereof

(i) Method for measurement

Spacers and the like are dispersed on a steel sheet having a smoothsurface, and one of spacers and the like is chosen. Then, the spacersand the like are compressed with the smooth end surface of a circularcylinder made of diamond and having a diameter of 50 μm by using acompression test machine (PCT-200 type Shimadzu Seisakusho Ltd.) at 20°C. A this time, the compression load is electrically detected aselectromagnetic magnetic force, and the compression displacement iselectrically detected by using a differential transformer.

As shown in FIG. 4, the spacers and the like are compressed to maximumload value (shown by a curve (a) in FIG. 4), and after that, the load isdecreased (shown by a curve (b) in FIG. 4). A this time, therelationship between the load and the compression displacement ismeasured with proviso that terminal point of reducing the load is notthe load value zero but refers to 0.1 g of the standard load value. Therecovery factor is defined as the ratio (L₂ /L₁) represented by %,wherein L₁ is a change until the maximum load point and L₂ is a changefrom the maximum load point to the standard load value.

(ii) Conditions for measurement

The maximum load value: 1 grf

Standard load value: 0.1 grf

Compression speed of application and removal of load: 0.27 grf/sec

Temperature of measuring room: 20° C.

As the spacers and the like of the present invention, inorganicparticles or synthetic resin particles can be used as long as theysatisfy the above K-value and the recovery factor. In particular, thesynthetic resin particles are preferred since the K-value and therecovery factor thereof can be readily adjusted in the above range.

The types of synthetic resins suitable for the formation of the spacersand like include the following various kinds of plastic materials:linear or cross-linked polymers such as polyethylene, polypropylene,polymethylpentene, polyvinylchloride, polytetrafluoroethylene,polystyrene, polymethyl methacrylate, polyethylene terephthalate,polybutylene terephthalate, polyamides, polyimides, polysulfone,polyphenyleneoxide, and polyacetal and resins having a net structuresuch as epoxy resins, phenol resins, melamine resins, unsaturatedpolyester resins, polydivinylbenzene; divinylbenzene-styrene copolymer,divinylbenzene-acrylate copolymers, polydiallylphthalate, polymer oftriallyl isocyanurate, and polymer of benzoguanamine.

Among the aforesaid resins, those especially desirable for the formationof the spacers are resins having a net structure such aspolydivinylbenzene, divinylbenzene-styrene copolymer,divinylbenzeneacrylate copolymers, and polydiallylphthalate.

There is no special limit to inorganic materials and conventional knownmaterials can be used.

Preferred shape of the spacer and the like is spherical. Diameters inthe range of 0.1 to 100 μm are preferred, more preferably in the rangeof 0.5 to 50 μm, and still more specifically in the range of 1 to 20 μm.

The colored spherical spacers for a liquid crystal display element ofthe present invention are colored. Examples of a method for coloringinclude staining, pigment mixing, polymerization of dye monomers, andoxidizing a metallic thin film formed on the spacers. The method forcoloring is disclosed, for example, in Japanese Laid-Open PatentPublication Nos. 57-189117, 63-89890, 1-144021, 1-144429, 63-66228,63-89408, 1-200227, 1-207719 and 2-214781. These methods for coloringcan be incorporated into the present invention.

The reason for using the colored spherical spacers as spacers for aliquid crystal display element of the present invention is as follows:

In the liquid crystal display element, the liquid crystal is opticallychanged to form an image by applying a voltage between the transparentelectrodes. However, spacers are not optically changed by theapplication of a voltage. Therefore, uncolored spacers are likely to beobserved as luminescent spots in dark portions of a displayed image,resulting in a deterioration in the contrast of the image display.

The adhesive coated spherical spacers for a liquid crystal displayelement of the present invention have adhesion when being heated.Examples of methods for providing the spacers with adhesion includeforming a waxy polyethylene layer, a hot-melt adhesive layer, or anepoxy adhesive layer on the surface of the core fine spheres.

Methods for providing adhesion are disclosed, for example, in JapaneseLaid-Open Utility Model Publication No. 51-22453, Japanese Laid-OpenPatent Publication Nos. 63-44631, 63-94224, 63-200126, 1-247154,1-247155 and 2-261537. These methods can be introduced into the presentinvention.

When the adhesive coated spherical spacers are used as the spacers for aliquid crystal display element, the spacers can be prevented from beingdisplaced in the gap between the substrates. As a result, the alignmentcoat are prevented from being damaged, and the image quality and thecell gap precision between the substrates are improved.

Core fine particles used for colored spherical spacers and adhesivecoated spherical spacers can be formed from the above spacers and thelike.

As described above, the spacers and the like of the present inventionhave a K-value in a predetermined range and a recovery factor after thecompression deformation in a predetermined range, so that these spacershave physical properties preferable as the spacers for a liquid crystaldisplay element. That is, since the hardness of these spacers isappropriate, they are not likely to damage the alignment coat when thesubstrates are applied with pressure in the course of the production ofthe liquid crystal display element.

Moreover, the spacers have an appropriate deformation property, so thatthe spacers come into contact with the substrates over a large area. Asa result, the spacers are not likely to be placed on the surfaces of thesubstrates due to gravity and minute vibrations. Furthermore, thealignment coat are prevented from being damaged by the movement of thespacers.

Since the spacers have appropriate hardness, when pressure is applied tothe pair of substrates facing each other, the applied pressure issupported by the spacers, whereby the gap between the substrates can beuniformly maintained. Accordingly, irregularity of the thickness of theliquid crystal layer can be reduced compared with the conventionalliquid crystal layer.

II. Liquid crystal display element

Hereinafter, an example of the liquid crystal element of the presentinvention will be described with reference to the drawings. The liquidcrystal display element of the present invention can have the sameconstruction as that shown in FIG. 7 except that the above-mentionedspherical spacers are used.

As shown in FIG. 1, a liquid crystal display element A comprises a pairof substrates 7, 9, spacers 8 disposed between the pair of substrates 7,9 so as to maintain a constant gap therebetween, nematic liquid crystal11, a sealing material 10 filled in the periphery of the gap between thepair of substrates 7, 9, and polarizing sheets 12, 13 coated on thesurfaces of the respective substrates 7, 9.

The above-mentioned substrates 7, 9 are formed by patterning transparentelectrodes 2, 5 made of ITO (Indium-Tin-Oxide) film on one surface oftheir respective transparent substrates 1, 4 made of glass and bycoating the surfaces of the transparent electrodes 2, 5 and thetransparent substrates 1, 4 with alignment coat (polyimide films 3, 6).The alignment coat 3, 6 are provided with alignment control by rubbing.

The spacers 8 have a K-value in the above-mentioned predetermined rangeand a recovery factor after the compression deformation in theabove-mentioned predetermined range. The spacers 8 may be colored and/ormay have adhesion.

According to the present invention, the liquid crystal display elementin which a clear image is obtained without image defects can beprovided.

III. Conductive fine spheres

The conductive fine spheres of the present invention have theabove-mentioned fine spheres and conductive layers formed on thesurfaces of the fine spheres. These conductive fine spheres can be usedfor the conductive connection between fine electrodes in the field ofelectronic mounting.

In the conductive fine spheres, as described above, the K-value at 10%compression deformation is in the range of 250 kgf/mm² to 700 kgf/mm².When the conductive fine spheres in this range are used, the facingelectrode surfaces are not damaged by the conductive fine spheres in thecourse of the production of the element in which a pair of electrodesare connected by the conductive fine spheres. Moreover, when the gapbetween the electrodes is adjusted by pressure pressing, the gap controlcan be readily performed. A more preferred K-value at 10% compressiondeformation is in the range of 350 kgf/mm² to 550 kgf/mm².

When the K-value is more than 700 kgf/mm², the conductive fine spheresdisposed between the two electrodes are not readily deformed by beingapplied with pressure. As a result, the contact area between theconductive fine spheres and the electrode surfaces does not spread,making it difficult to reduce contact resistance. Moreover, when excessload is applied in order to deform the conductive fine spheres, theconductive layers formed on The surfaces of the conductive fine spheresare torn up or peeled off, damaging The electrode surfaces in the courseof the production of the element.

When the conductive fine spheres having a K-value less than 250 kgf/mm²disposed between two electrodes are applied with a compression load, thecompression deformation often becomes great, so that the conductivelayers formed on the surfaces of The conductive fine spheres do notfollow This deformation. As a result, there is a possibility that theconductive layers are torn up or peeled off. Moreover, when the amountof compression deformation becomes great and the conductive fine spheresflatten, the electrodes come into contact with each other, causingunsatisfactory minute electrode connection.

Furthermore, in the conductive fine spheres of the present invention,the recovery factor after the compression deformation of the conductivefine spheres is in the range of 30% to 80% at 20° C. The range of 40% to70% is especially preferred.

When adhesive, in which the conductive fine spheres having the recoveryfactor more than 80% are dispersed, is disposed between two electrodes,these electrodes are contacted to each other by pressing, and thepressure is removed after the adhesive is hardened, the conductive finespheres after being deformed by compression readily return to theiroriginal shape, so that the adhesive layers are likely to be peeled offfrom the electrode surfaces.

In the element produced by a method, in which adhesive with theconductive fine spheres having the recovery factor less than 30%dispersed therein are filled between two electrodes, these electrodescontact each other by pressing, and the pressure is removed after theadhesive is hardened, the adhesive layers continue to contract andexpand under the repetition of cooling and heating. However, theconductive fine spheres remain deformed by compression, so that a gap isgenerated between the surfaces of the electrodes when the adhesivelayers expand, causing contact defects.

The conductive fine spheres of the present invention can be made ofinorganic materials or synthetic resins as long as they satisfy theK-value and the recovery factor in the above-mentioned range. As thefine spheres forming these conductive fine spheres, the same kind ofspacers and the like as that mentioned above can be used. Examples ofpreferred resins for forming the fine spheres include resins having anet structure such as polydivinylbenzene, divinylbenzenestyrenecopolymer, divinylbenzene-acrylate copolymers, and polydiallylphthalate.

The particle diameter of the fine spheres is in the range of 0.1 to 100μm, preferably in the range of 0.5 to 50 μm, and more preferably in therange of 1 to 20 μm.

The thickness of the conductive layers is preferably in the range of0.02 to 5 μm. When the thickness is less than 0.02 μm, it is difficultto obtain the desired conductivity. When the thickness is more than 5μm, the conductive layers are likely to be peeled off from the surfacesof the fine spheres due to the difference of the thermal expansioncoefficient between the fine spheres and the conductive layers.

Examples of metals used for the conductive layers include Ni, Au, Ag,Cu, Co, Sn, In, or alloy including one or more of these metals as itsmain component. In particular, indium is preferred.

Examples of methods for forming metal layers on the surfaces of the finespheres include an electroless plating (chemical plating), a coatingmethod in which paste obtained from metal powders alone or metal powdersmixed with binders is coated on the fine spheres; and a physicaldeposition method such as vacuum deposition, ion plating, and ionsputtering.

A method for forming a metal layer by the electroless plating will bedescribed by way of illustrating an example using gold substitutionplating.

This method is divided into the following: an etching step, anactivation step, a chemical nickel plating step and an gold substitutionplating step.

In the etching step, unevenness is formed on the surfaces of the finespheres so that plated layers adhere to the fine spheres. Examples ofetchant include caustic soda aqueous solution, concentrated hydrochloricacid, concentrated sulfuric acid, and chromic anhydride.

In the activation step, catalytic layers are formed on the surfaces ofthe etched fine spheres, and the catalytic layers are activated. Theactivation of the catalytic layers promotes the deposition of metallicnickel in the chemical nickel plating step described later. Thecatalytic layers formed on the surfaces of the fine spheres, includingPd²⁺ and Sn²⁺ are treated with concentrated sulfuric acid orconcentrated hydrochloric acid, and Sn²⁺ alone is removed bydissolution, thereby metallizing Pd²⁺. The metallized palladium isactivated with a palladium activator such as concentrated caustic sodasolution and sensitezed.

In the chemical nickel plating step, metallic nickel layers are furtherformed on the surfaces of the fine spheres on which the catalytic layersare formed. For example, nickel chloride is reduced with sodiumhypophosphite, and nickel is deposited on the surfaces of the finespheres.

In the gold substitution plating step, the fine spheres coated withnickel are put in gold potassium cyanide aqueous solution, and nickel iseluted under rising temperature, thereby depositing on the surfaces ofthe fine spheres.

When the conductive layers are formed from indium-plated layers, thethickness of the conductive layers are preferably in the range of 0.02to 5 μm. When the thickness of the conductive layers is less than 0.02μm, it is difficult to obtain the desired conductivity. When thethickness of the conductive layers is more than 5 μm, and a pair ofelectrodes sandwiching conductive fine spheres therebetween are pressed,elasticity of the conductive fine spheres cannot be effectivelyexhibited. When the thickness of the conductive layers is more than 5μm, the conductive fine spheres are likely to aggregate.

Examples of methods for forming indium-plated layers on the surfaces ofthe fine spheres are as follows:

(1) Method for forming indium-plated layers by electroless plating

Thin films made of metal (e.g. Cu) whose ionization tendency is greaterThan that of indium are previously formed on the surfaces of the finespheres, and then this metal is replaced with indium.

    3Cu.sup.- +2In.sup.+++ →3Cu.sup.++ +2In↓

(2) Method for reduction plating

A reducer is added to an aqueous solution of indium salt and indium isdeposited on the surfaces of the fine spheres by a reduction reaction,thereby forming indium-plated layers.

Alternatively, thin films made of metal such as nickel is previouslyformed on the surfaces of the fine spheres, after which indium isdeposited on the surfaces by the reduction reaction, thereby formingindium-plated layers.

(3) Method for forming indium-plated layers by mechanical and physicaltechniques

The fine spheres and indium fine particles are mixed, and then theindium fine particles are collided with or rubbed into the surfaces ofthe fine spheres by using hybridization on mechanofusion, therebyforming indium thin films on the surfaces of the fine spheres.Alternatively, the fine spheres and the indium fine particles are mixed,and then they are heated to melt the indium, thereby coating the indiumthin films on the surfaces of the fine spheres.

The element can be produced by using conductive fine spheres thusobtained. This element can be produced, for example, as follows:

As shown in FIG. 5, an insulating binder 28 in which conductive finespheres 29 are uniformly dispersed is coated on electrodes 24 by screenprinting or a dispenser, or the conductive fine spheres 29 alone aredisposed on the electrodes 24 without using the binder 28. In the caseof the latter, the conductive fine spheres 29 can be dispersed fromabove the electrodes 24 or the conductive fine spheres 29 are charged tobe electrostatically attached onto the electrodes 24.

Next, electrodes 25 are superimposed over the above electrodes 24. Underthis condition, the electrodes 24 and 25 are applied with pressure. Itis not required to apply great pressure. A pressure which maintains thecontact condition between the conductive fine spheres 29 and thesurfaces of the electrodes 24 and 25 can be applied. Then, a laminationin which the conductive fine spheres 29 are sandwiched between the pairof the electrodes 24 and 25 is heated. Press heating is preferred. Asdescribed above, an element B is obtained as shown in FIG. 5.

Examples of electrodes used for the above element include electrodes inwhich ITO thin films are formed on glass plates, electrodes in whichaluminum thin films are formed on glass plates, electrodes produced byattaching Cu sheets on plastic films, followed by etching, andelectrodes produced by printing silver paste and carbon black on films.In this way, predetermined portions between the electrodes of a liquidcrystal display element can be electrically connected by using theconductive fine spheres.

Since the conductive fine spheres of the present invention can bedeformed by compression to an appropriate degree, when the electrodesare connected by using the conductive fine spheres, the contact areasbetween the conductive fine spheres and the surfaces of the electrodesare enlarged, thereby reducing contact resistance. Moreover, therecoverability from the deformation by the compression of the conductivefine spheres is appropriate. Therefore, when the compression loadapplied on the electrodes is removed in the course of the connectionbetween the electrodes by using the conductive fine spheres, a gap isnot formed between the conductive fine spheres and the surfaces of theelectrodes, eliminating contact defects.

As described above, the conductive fine spheres of the present inventionhave appropriate compression deformation properties and recoverabilityfrom deformation, so that when the conductive fine spheres sandwichedbetween the electrodes are used, they exhibit excellent non-isotropicconductivity and connection reliability. Thus, they are applicable tothe following uses.

(1) Transfer materials for electrically connecting upper and lowerelectrodes in a liquid crystal display element.

(2) Materials for a COG (chip on glass) connection between an LSI and aglass substrate on which electrodes are formed in a liquid crystaldisplay element.

(3) Materials for electrically connecting a glass substrate on whichelectrodes are formed and a flexible printed circuit in a liquid crystaldisplay element.

(4) Materials for a COB (chip on board) or C0F (chip on film) connectionbetween board-shaped or a film-shaped substrate und an LSI.

Examples

Hereinafter, the present invention will be described by way ofillustrating examples.

The test method is as follows:

(A) Measurement of mean particle size

This was performed with a Coulter Counter Model ZB/C-1000 particle sizemeasuring apparatus (manufactured by Coulter Electronics Co., Ltd.).

(B) Compression test for spacers

This was performed with a compression test machine (manufactured byShimadzu Seis a kusho Ltd.).

(C) Measurement of the cell gap between upper and lower substrates of aliquid crystal cell

This was performed with a Liquid Crystal Cell Gap Measurement Apparatus(Trade Name TFM-120 AFT, manufactured by Oak Seisa kusho Ltd.).

(D) Display performance of a liquid crystal display element

A polarizing sheet was applied to both upper and lower surfaces of aliquid crystal cell so that the color tone of light reflected from theliquid crystal cell becomes olive color. Then, the color irregularity indensity was observed in the polarizing sheet. Moreover, the liquidcrystal display element was connected with a power source to be lit up,and the image obtained was observed.

Example 1

Tetramethylolmethane tetraacrylate was polymerized by suspensionpolymerization, after which spacers having a mean particle diameter of7.03 μm (standard deviation 0.27 μm) were selected by theclassification.

These spacers were subjected to a compression test. The K-value at 10%compression deformation was 550 μkgf/mm². Also, in the case of themaximum load value of 1 grf, the recovery factor after the compressiondeformation was 65%.

A transparent conductive film of the indium oxide-tin oxide type havinga thickness of about 500 Å was formed on a glass plate having athickness of 0.7 mm by the low temperature sputtering method. Afterthat, a predetermined electrode pattern was formed on the glass plate byphotolithography. Then, an alignment agent was coated on the glassplate, and an alignment coat was formed by heating. The resulting glassplate was cut into a size of 5 cm× 12.5 cm to obtain a glass substratefor a liquid crystal display element.

An epoxy adhesive in which glass fiber spacers were mixed was printed atthe periphery of this glass substrate to a thickness of 1 mm by screenprinting.

The glass substrate was horizontally placed, and then the spacersobtained were dispersed from above by pressurized nitrogen gas and wereuniformly dropped onto the glass substrate. The dispersion time wasadjusted so that the dispersion concentration of the spacers on theglass substrate was about 100 spacers/mm².

Another glass substrate was superimposed over the above glass substrateon which the spacers were dispersed, and the entire glass substratessustained a load of 1 kg weight/cm² uniformly applied by a pressmachine. At the same time, the glass substrates were heated to 160° C.for 20 minutes to harden the epoxy adhesive at the periphery thereof.

A cell thus produced was evacuated so that the inside thereof became avacuum, and then liquid crystal was drawn inside through a hole providedin a part of a peripheral sealing portion. The gap between the upper andthe lower substrates of the liquid crystal cell thus produced wasmeasured to obtain a cell gap value in the range of 6.98±0.03 μm.

A polarizing sheet was applied to the upper and the lower surfaces ofthis liquid crystal cell so hat the color tone of light reflected fromthe liquid crystal cell became olive color. This olive color was evenwith no irregularity in density. Moreover, the liquid crystal displayelement was connected with a power source to be lit up, and asatisfactory display performance was observed.

Example 2

First, 75% by weight of tetramethylolmethane tetraacrylate and 25% byweight of divinylbenzene were polymerized by suspension polymerization,and after that spacers having a mean particle diameter of 7.05 μm(standard deviation 0.25 μm) were selected by the classification.

The K-value of the spacers at 10% compression deformation was 450μkgf/mm². Also, the recovery factor of the spacers after the compressiondeformation was 54%.

The cell gap value of the liquid crystal cell produced in the same wayas in Example 1 except hat the above spacers were used was in the rangeof 6.88 ±0.03 μm. Also, color irregularity in density was not observedwhen the polarizing sheet was applied to the liquid crystal cell in thesame way as in Example 1, and the display performance was good when itwas lit up.

Example 3

First, 50% by weight of tetramethylolmethane tetraacrylate and 50% byweight of divinylbenzene were polymerized by suspension polymerization,and after that spacers having a mean particle diameter of 7.02 μm(standard deviation 0.26 μm) were selected by the classification.

The K-value of the spacers at 10% compression deformation was 390kgf/mm². Also, the recovery factor of the spacers after the compressiondeformation was 50%.

The cell gap value of the liquid crystal cell produced in the same wayas in Example 1 except that the above spacers were used was in the rangeof 6.83±0.04 μm. Also, color irregularity in density was not observedwhen the polarizing sheet was applied to the liquid crystal cell in thesame way as in Example 1, and the display performance was good when itwas lit up.

Example 4

First, 25% by weight of tetramethylolmethane tetraacrylate and 75% byweight of divinylbenzene were polymerized by suspension polymerization,and after that spacers having a mean particle diameter of 7.03 μm(standard deviation 0.28 μm) were selected by the classification.

The K-value of the spacers at 10% compression deformation was 380kgf/mm². Also, the recovery factor of the spacers after the compressiondeformation was 45%.

The gap value of the liquid crystal cell produced in the same way as inExample 1 except that the above spacers were used was in the range of6.80±0.03 μm. Also, color irregularity in density was not observed whenthe polarizing sheet was applied to the liquid crystal cell in the sameway as in Example 1, and the display performance was good when it waslit up.

Example 5

Divinylbenzene was polymerized by suspension polymerization, and afterthat spacers having a mean particle diameter of 7.05 μm (standarddeviation 0.29 μm) were selected by the classification.

The K-value of the spacers at 10% compression deformation was 280kgf/mm². Also, the recovery factor of the spacers after the compressiondeformation was 35%.

The gap value of the liquid crystal cell produced in the same way as inExample 1 except hat the above spacers were used was in the range of6.78±0.06 μm. Also, color irregularity in density was not observed whenthe polarizing sheet was applied to the liquid crystal cell in the sameway as in Example 1, and the display performance was good when it waslit up.

Comparative Example 1

A liquid crystal display element was obtained in the same way as inExample 1 except that spacers made of benzoguanamine polymers and havinga mean particle diameter of 6.98 μm (standard deviation 0.25 μm) wereused.

The K-value of the spacers at 10% compression deformation was 600kgf/mm² and the recovery factor of the spacers after the compressiondeformation was 13%.

The cell gap value of the liquid crystal cell produced in the same wayas in Example 1 except that the above spacers were used was in the rangeof 6.92 ±0.07 μm. The color irregularity in density was observed whenthe polarizing sheet was applied to the liquid crystal cell in the sameway as in Example 1, and the display performance was unsatisfactory whenit was lit up.

Comparative Example 2

First, 30% by weight of triallyl isocyanurate and 70% by weight ofdiallyl phthalate were polymerized by suspension polymerization, andafter that spacers having a mean particle diameter of 7.03 μm (standarddeviation 0.28 μm) were obtained. The K-value of the spacers at 10%compression deformation was 240 kgf/mm². Also, the recovery factor ofthe spacers after the compression deformation was 12%.

The cell gap value of the liquid crystal cell produced in the same wayas in Example 1 except that the above spacers were used was in the rangeof 6.89 ±0.03 μm. The color irregularity in density was observed whenthe polarizing sheet was applied to the liquid crystal cell in the sameway as in Example 1, and the display performance was unsatisfactory whenit was lit up.

Comparative Example 3

Spherical spacers were obtained in the same way as in Example 1 exceptthat spacers made of polystyrene and having a mean particle diameter of6.98 μm (standard deviation 0.25 μm) were used.

The K-value of the spacers at 10% compression deformation was 105kgf/mm². The recovery factor of the spacers after the compressiondeformation was unmeasurable.

The cell gap value of the liquid crystal cell produced in the same wayas in Example 1 except that the above spacers were used was in the rangeof 6.75±0.07 μm. The color irregularity in density was observed when thepolarizing sheet was applied to the liquid crystal cell in the same wayas in Example 1, and the display performance was unsatisfactory when itwas lit up.

Comparative Example 4

A liquid crystal display element was obtained in the same way as inExample 1 except that spacers made of benzoguanamine polymers and havinga mean particle diameter of 7.05 μm (standard deviation 0.25 μm) wereused.

The K-value of the spacers at 10% compression deformation was 620kgf/mm², and the recovery factor of the spacers after the compressiondeformation was 13%.

The cell gap value of the liquid crystal cell produced in the same wayas in Example 1 except that the above spacers were used was in the rangeof 6.88±0.05 μm. The color irregularity in density was observed when thepolarizing sheet was applied to the liquid crystal cell in the same wayas in Example 1, and the display performance was unsatisfactory when itwas lit up.

Comparative Example 5

A liquid crystal display element was obtained in the same way as inExample 1 except that spacers made of silicon dioxide and having a meanparticle diameter of 7.01 μm (standard deviation 0.19 μm) were used.

The K-value of the spacers at 10% compression deformation was 5000kgf/mm², and the recovery factor of the spacers after the compressiondeformation was 85%.

The cell gap value of the liquid crystal cell produced in the same wayas in Example 1 except that the above spacers were used was in the rangeof 6.99±0.10 μm. The color irregularity in density was observed when thepolarizing sheet was applied to the liquid crystal cell in the same wayas in Example 1, and the display performance was unsatisfactory when itwas lit up.

Example 6

First, tetramethylolmethane triacrylate was polymerized by suspensionpolymerization, and after that resin fine particles having a meanparticle diameter of 7.03 μm (standard deviation 0.27 μm) were selectedby the classification. 100 g of concentrated sulfuric acid was added to10 g of these fine particles. The mixture was reacted with acid at 55°C. for 6 hours.

Next, 6 g of a basic dye (CATIRON BLACK SBH) (manufactured by HodogayaKagaku Co., Ltd.) was dissolved in 300 ml of water, and a dye bathsolution was obtained by adjusting this solution to pH4 with aceticacid. Then, the aforesaid acid-treated fine particles were added to thisdye bath solution, and a dyeing treatment was performed at 95° C. for 6hours to obtain black spherical spacers. A mean particle diameter and astandard deviation of the spacers were 7.38 μm and 0.29 μm,respectively.

The K-value of the colored spacers at 10% compression deformation was520 kgf/mm². Also, the recovery factor of the colored spacers after thecompression deformation was 55% in the case of the maximum load value of1 grf.

A liquid crystal display element was obtained in the same way as inExample 1 except that the above-mentioned spacers were used. The cellgap value of the liquid crystal cell was in the range of 6.98±0.03 μm.

Also, color irregularity in density was not observed when The polarizingsheet was applied to the liquid crystal cell in the same way as inExample 1, and the display performance was good when it was lit up.

Example 7

First, 75% by weight of tetramethylolmethane tetraacrylate and 25% byweight of divinylbenzene were polymerized by suspension polymerization,and after that spacers having a mean particle diameter of 7.05 μm(standard deviation 0.25 μm) were selected by the classification. Thesespacers were dyed in the same way as in Example 6 to obtain blackspherical spacers. A mean particle diameter and a standard deviation ofthe spherical spacers were 7.04 μm and 0.27 μm, respectively.

The K-value of the spacers at 10% compression deformation was 420kgf/mm². Also, the recovery factor of the spacers after the compressiondeformation was 51%.

The cell gap value of the liquid crystal cell produced in the same wayas in Example 1 except that the above-mentioned spacers were used was inthe range of 7.22±0.03 μm. Also, color irregularity in density was notobserved when the polarizing sheet was applied to the liquid crystalcell in the same way as in Example 1, and the display performance wasgood when it was lit up.

Example 8

First, 50% by weight of tetramethylolmethane tetraacrylate and 50% byweight of divinylbenzene were polymerized by suspension polymerization,and after that spacers having a mean particle diameter of 7.02 μm(standard deviation 0.26 μm) were selected by the classification. Thesespacers were dyed in the same way as in Example 6 to obtain blackspherical spacers. A mean particle diameter and a standard deviation ofthe spherical spacers were 7.47 μm and 0.28 μm, respectively.

The K-value of the spacers at 10% compression deformation was 370kgf/mm². Also, the recovery factor of the spacers after the compressiondeformation was 47%.

The cell gap value of the liquid crystal cell produced in the same wayas in Example 1 except that the above-mentioned spacers were used was inthe range of 6.83±0.04 μm. Also, color irregularity in density was noobserved when the polarizing sheet was applied to the liquid crystalcell in the same way as in Example 1, and the display performance wasgood when it was lit up.

Example 9

First, 25% by weight of tetramethylolmethane tetraacrylate and 75% byweight of divinylbenzene were polymerized by suspension polymerization,and after that spacers having a mean particle diameter of 7.03 μm(standard deviation 0.28 μm) were selected by the classification. Thesespacers were dyed in the same way as in Example 6 to obtain blackspherical spacers. A mean particle diameter and a standard deviation ofthe spherical spacers were 7.45 μm and 0.30 μm, respectively.

The K-value of the spacers at 10% compression deformation was 360kgf/mm². Also, the recovery factor of the spacers after the compressiondeformation was 45%.

The cell gap value of the liquid crystal cell produced in the same wayas in Example 1 except that the above-mentioned spacers were used was inthe range of 6.80±0.03 μm. Also, color irregularity in density was notobserved when the polarizing sheet was applied to the liquid crystalcell in the same way as in Example 1, and the display performance wasgood when it was lit up.

Example 10

First, divinylbenzene was polymerized by suspension polymerization, andafter that spacers having a mean particle diameter of 7.05 μm (standarddeviation 0.29 μm) were selected by the classification. These spacerswere dyed in the same way as in Example 6 to obtain black sphericalspacers. A mean particle diameter and a standard deviation of thespherical spacers were 7.40 μm and 0.30 μm, respectively.

The K-value of the spacers at 10% compression deformation was 270kgf/mm². Also, the recovery factor of the spacers after the compressiondeformation was 40%.

The cell gap value of the liquid crystal cell produced in the same wayas in Example 1 except that the above-mentioned spacers were used was inthe range of 7.12±0.05 μm. Also, color irregularity in density was notobserved when the polarizing sheet was applied to the liquid crystalcell in the same way as in Example 1, and the display performance wasgood when it was lit up.

Comparative Example 6

First, spacers made of benzoguanamine copolymers and having a meanparticle diameter of 6.98 μm (standard deviation 0.25 μm) were dyed redwith an acid dye to obtain colored spacers. The colored spacers had amean particle diameter of 7.01 μm (standard deviation 0.27 μm).

The K-value of the spacers at 10% compression deformation was 580kgf/mm². Also, the recovery factor of the spacers after the compressiondeformation was 11%.

The cell gap value of the liquid crystal cell produced in the same wayas in Example 1 except that the above-mentioned spacers were used was inthe range of 6.96±0.08 μm. Also, color irregularity in density wasobserved when the polarizing sheet was applied to the liquid crystalcell in the same way as in Example 1, and the display performance wasunsatisfactory when it was lit up.

Comparative Example 7

First, 30% by weight of triallyl isocyanurate and 70% by weight ofdiallyl phthalate were polymerized by suspension polymerization, andafter that spacers having a mean particle diameter of 7.03 μm (standarddeviation 0.26 μm) were selected by the classification. These spacerswere dyed in the same way as in Example 6 to obtain black sphericalspacers. A mean particle diameter and a standard deviation of thespherical spacers were 7.38 μm and 0.27 μm, respectively.

The K-value of the spacers at 10% compression deformation was 220kgf/mm². Also, the recovery factor of the spacers after the compressiondeformation was 12%.

The cell gap value of the liquid crystal cell produced in the same wayas in Example 1 except that the above-mentioned spacers were used was inthe range of 7.23±0.04 μm. Also, color irregularity in density wasobserved when the polarizing sheet was applied to the liquid crystalcell in the same way as in Example 1, and the display performance wasunsatisfactory when it was lit up.

Comparative Example 8

First, black spherical spacers were obtained in the same way as inExample 6 except that the spacers made of polystyrene and having a meanparticle diameter of 6.98 μm (standard deviation 0.25 μm) were used. Thecolored spacers had a mean particle diameter of 7.47 μm (standarddeviation 0.29 μm). The K-value of the colored spacers at 10%compression deformation was 100 kgf/mm². Also, the recovery factor ofthe spacers after the compression deformation was not measurable.

The cell gap value of the liquid crystal cell produced in the same wayas in Example 1 except that the above-mentioned spacers were used was inthe range of 6.75±0.07 μm. Also, color irregularity in density wasobserved when the polarizing sheet was applied to the liquid crystalcell in the same way as in Example 1, and the display performance wasunsatisfactory when it was lit up.

Comparative Example 9

A liquid crystal display element was obtained in the same way as inExample 1 except that spacers made of benzoguanamine polymers and havinga mean particle diameter of 7.05 μm (standard deviation 0.25 μm). Thespacers were dyed in the same was as n Comparative Example 6 obtain redspherical spacers. A mean particle diameter and a standard deviation ofthe spherical spacers were 7.08 μm and 0.27 μm, respectively. TheK-value of the colored spacers at 10% compression deformation was 605kgf/mm², and the recovery factor of the colored spacers after thecompression deformation was 11%.

The cell gap value of the liquid crystal cell produced in the same wayas in Example 1 except that the above-mentioned spacers were used was inthe range of 6.91±0.08 μm. Also, color irregularity in density wasobserved when the polarizing sheet was applied to the liquid crystalcell in the same way as in Example 1, and the display performance wasunsatisfactory when it was lit up.

Comparative Example 10

First, spacers made of silicon dioxide and having a mean particlediameter of 7.01 μm (standard deviation of 0.19 μm) were dyed with abasic dye to obtain blue spherical spacers. A mean particle diameter anda standard deviation of the colored spacers were 7.04 μm and 0.21 μm,respectively. The K-value of the colored spacers at 10% compressiondeformation was 5000 kgf/mm², and the recovery factor of the spacersafter the compression deformation was 85%.

The cell gap value of the liquid crystal cell produced in the same wayas in Example 1 except that the above-mentioned spacers were used was inthe range of 7.00±0.10 μm. Also, color irregularity in density wasobserved when the polarizing sheet was applied to the liquid crystalcell in the same way as in Example 1, and the display performance wasunsatisfactory when it was lit up.

Example 11

First, 75% by weight of tetramethylolmethane tetraacrylate and 25% byweight of divinylbenzene were polymerized by suspension polymerization,and after that fine particles having a mean particle diameter of 10.00μm (standard deviation 0.40 μm) were selected by the classification.

Then, a solution prepared by dissolving 0.15 g of tetrapropoxytitanium(Trade name A-1, manufactured by Nippon Soda Co., Ltd.) in 15 ml ofn-hexane was added to 10 g of the fine particles, and were well mixedwith a spatula, after which the n-hexane was evaporated. Next, thismixture was thoroughly ground in a mortar, eliminating any lumps.

Then, 2.6 g of waxy polyethylene (Trade name SANWAX 151-P, manufacturedby Sanyo Kasei Kogyo Co., Ltd.) was added to toluene as a hot-meltadhesive resin, and was dissolved in a hot bath at 80° C. To thissolution was added the above resin fine particles treated with anorganic titanium compound, and dispersed until the solution wascompletely emulsified, after which the solution was dried by heatingunder reduced pressure of 300 mm/Hg at 90° C.

In this way, the lumps in which the resin fine particles were coatedwith the hot-melt adhesive resin was obtained. Next, 20 ml of glycerinswas added to the lumps and the lumps were thoroughly ground in a mortar.Furthermore, the lumps were passed through three sets of rollers to becompletely decomposed.

Next, the decomposed lumps were washed on a glass filter with 1 liter ofethanol and were suspended in a mixed ethanol/Freon-113 solution (volumeratio 2:1). The mixture was then left standing undisturbed in this statefor 15 hours, and the supernatant was decanted to remove minute flakesof waxy polyethylene. The remaining decomposed lumps were again filteredwith a glass filter, then washed with Freon-113, and dried in a gearoven at 60° C. to obtain coated resin fine particles.

The coated resin fine particles had a mean particle diameter of 10.42 μm(standard deviation 0.43 μm). As a result, it was found that waxypolyethylene was formed on the surfaces of The resin fine particles toan average thickness of 0.16 μm. The observation of the surfaces of thecoated resin fine particles by using a scanning electron microscopeshowed that the surfaces of the resin fine particles were uniformlycoated with waxy polyethylene without any gaps.

The K-value of the coated resin fine particles at 10% compressiondeformation was 450 kgf/mm², and the recovery factor of the particlesafter the compression deformation in the case of the maximum load valueof 1 grf was 63%.

A liquid crystal display element was obtained in the same way as inExample 1 except that the above coated resin fire particles spacers wereused as spacers. The cell gap value of the liquid crystal cell was inthe range of 9.95±0.03 μm.

Also, color irregularity in density was not observed when the polarizingsheet was applied to the liquid crystal cell in the same way as inExample 1, and the display performance was good when it was lit up.

Example 12

First, divinylbenzene was polymerized by suspension polymerization, andafter that fine particles having a mean particle diameter of 9.90 μm(standard deviation 0.36 μm) were selected by the classification. Asolution prepared by dissolving 0.15 g of tetrapropoxytitanium (Tradename A-1, manufactured by Nippon Soda Co., Ltd.) in 15 ml of n-hexanewas added to 10 g of the fine particles, and were well mixed with aspatula, after which the n-hexane was evaporated. Next, this mixture wasthoroughly ground in a mortar, eliminating the lumps.

Then, 2 g of solid epoxy resin with an epoxy equivalent of 480 and asoftening point of 68° C. (Trade name EPICOAT 1001, manufactured by YukaShell Epoxy, Co., Ltd.) was dissolved in 40 ml of acetone, and to thissolution was added 6 ml of water, 10 g of the aforesaid fine particles,and as a hardening agent, 0.4 g of 2-ethyl-4-methylimidazole 2E4MZ.After through mixing, the acetone was evaporated, while stirring. Then,the dried material was crushed in a mortar and the lumps were completelydemolished.

The mean particle diameter of the coated resin fine particles soobtained was 10.32 μm (standard deviation 0.46 μm). From this result,the thickness of the adhesive epoxy resin layer was calculated to be0.21 μm. Examination of the surfaces of these coated resin fineparticles with a scanning electron microscope revealed that the surfacesof the resin fine particles were uniformly coated with the epoxy resinlayers without any gaps.

The K-value of the coated resin fine particles at 10% compressiondeformation was 420 kgf/mm², and the recovery factor of the particlesafter the compression deformation in the case of the maximum load valueof 1 grf was 52%.

A liquid crystal display element was obtained in the same way as inExample 1 except that the above coated resin fine particles were used asspacers. The cell gap value of the liquid crystal cell was in the rangeof 9.83±0.03 μm.

Also, color irregularity in density was not observed when the polarizingsheet was applied to the liquid crystal cell in the same way as inExample 1, and the display performance was good when it was lit up.

Comparative Example 11

First, inorganic fine particles made of glass silicate and having a meanparticle diameter of 7.30 μm (standard deviation 0.32 μm) were obtained.Then, a solution prepared by dissolving 0.35 g of tetrapropoxytitanium(Trade name B-1, manufactured by Nippon Soda Co., Ltd.) in 15 ml ofn-hexane was added to 10 g of the inorganic fine particles, and werewell mixed with a spatula, after which the n-hexane was evaporated.Next, this mixture was thoroughly ground in a mortar, eliminating thelumps.

Then, 2.9 g of carboxyl group-containing ethylene-vinyl acetatecopolymer (Trade name DUMILAN C-2280, manufactured by Takeda YakuhinKogyo Co., Ltd. ) was used as a hot-melt adhesive resin.

The coated inorganic fine particles were obtained in the same way as inExample 11 except for the above. The examination of the surfaces of thecoated inorganic resin fine particles by the scanning electronmicroscope revealed that the thickness of the hot-melt adhesive layersformed on the coated inorganic fine particles were 0.43 μm.

The K-value of the coated inorganic fine particles at 10% compressiondeformation was 5500 kgf/ mm², and the recovery factor of the particlesafter the compression deformation in the case of the maximum load valueof 1 grf was 85%.

A liquid crystal display element was obtained in the same way as inExample 1 except that the above coated inorganic fine particles wereused as spacers. The cell gap value of the liquid crystal cell was inthe range of 7.25±0.03 μm.

Also, color irregularity in density was observed when the polarizingsheet was applied to the liquid crystal cell in the same way as inExample 1, and the display performance was unsatisfactory when it waslit up.

Comparative Example 12

First, as solid particles, inorganic fine particles made of glasssilicate and having a mean particle diameter of 7.30 μm (standarddeviation 0.32 μm) were obtained. A solution prepared by dissolving 0.35g of tetra propoxytitanium (Trade name B-1, manufactured by Nippon SodaCo., Ltd.) in 15 ml of n-hexane was added to 10 g of the inorganic fineparticles, and were well mixed with a spatula, after which the n-hexanewas evaporated. Next, This mixture was thoroughly ground in a mortar,eliminating the lumps.

Then, as a hardening agent, 0.2 g of dicyandiamide (Trade name DICY-7,manufactured by Yuka Shell Epoxy, Co., Ltd. ) and 0.2 g of2-phenylimidazole-4,5-diyldimethanol (Trade name 2PHZ, manufactured byShikoku Kasei Kogyo Co., Ltd. ) were used.

The coated inorganic fine particles were obtained in the same way as inExample 12 except for the above. The examination of the surfaces of thecoated inorganic fine particles by the scanning electron microscoperevealed that the thickness of the adhesive epoxy resin layers formed onthe coated inorganic fine particles were 0.41 μm.

The K-value of the coated inorganic fine particles at 10% compressiondeformation was 5300 kgf/ mm², and the recovery factor of the particlesafter the compression deformation in the case of the maximum load valueof 1 grf was 87%.

The liquid crystal display element was obtained in the same way as inExample 1 except that the above coated inorganic fine particles wereused as spacers. The cell gap value of the liquid crystal cell was inThe range of 7.23±0.03 μm.

Also, color irregularity in density was observed when the polarizingsheet was applied To the liquid crystal cell in the same way as inExample 1, and the display performance was unsatisfactory when it waslit up.

Example 13

First, tetramethylolmethane tetraacrylate was polymerized by suspensionpolymerization, and after that fine particles having a mean particlediameter of 6.98 μm (standard deviation 0.23 μm) were selected by theclassification. The K-value of the fine particles at 10% compressiondeformation was 633 kgf/mm² and the recovery factor after thecompression deformation in the case of the maximum load value of 1 grfwas 63%.

The resin fine particles were subjected to electroless nickel plating,after which conductive fine particles on which nickel-gold plated layerswere formed were obtained by the gold substitution reaction. Theanalysis of the conductive fine particles showed that gold content andnickel content were 28.0% by weight and 23.8% by weight. A mean particlediameter was 7.24 μm (standard deviation 0.28 μm).

Then, 1 g of the conductive fine particles and 0.5 g of glass fibers(diameter: 5.5 μm, average length: 27.5 m) were mixed with 75 g of epoxyresin (Trade name SE-4500, manufactured by Yoshikawa Kagaku Kogyo Co.,Ltd.) and 25 g of a hardening agent to form a paste. Next, as shown inFIG. 6, the paste 13 was coated to a predetermined thickness on a glasselectrode 12 comprising an ITO film on an inner surface thereof, andanother ITO electrode 14 was superimposed. This lamination wassandwiched by a press machine and press heated a 35 kg/cm² and 160° C.

A test chip C so produced was tested through 240 cycles by using athermal shock testing apparatus (Trade name TSV-40, manufactured byTabai Espec Corp.) which operates at 90° C. for one hour and at -4° C.for one hour.

Another test chip produced in the same way as the above was put in athermo-hygrostat (Trade name PR-3F, manufactured by Tabai Espec Corp.)which operates under the conditions of 80° C. and 90% RH and Tested for500 hours. The contact resistance between two electrodes were measuredbefore and after the thermal shock test and the moisture proof test byusing the four terminal method. The results are shown in Table 1. Fromthe results, it was found that the contact reliability of the conductivefine particles were excellent.

Example 14

First, 75% by weight of tetramethylolmethane tetraacrylate and 25% byweight of divinylbenzene were polymerized by suspension polymerization,and after that fine particles having a mean particle diameter of 7.05 μm(standard deviation 0.25 μm) were selected by the classification. TheK-value of the fine particles a 10% compression deformation was 527kgf/mm² and the recovery factor after The compression deformation in Thecase of the maximum load value of 1 grf was 55%.

The resin fine particles were subjected to electroless nickel plating,after which conductive fine particles on which nickel-gold plated layerswere formed were obtained by the gold substitution reaction. Theanalysis of the conductive fine particles showed that gold content andnickel content were 29.1% by weight and 23.4% by weight, respectively.The mean particle diameter was 7.29 μm (standard deviation 0.29 μm).

A test chip was obtained in the same way as in Example 13 except thatthe above conductive fine particles were used. The reliability of thistest chip was tested. The results are shown in Table 1. From theresults, it was found that the contact reliability of the conductivefine particles was excellent.

Example 15

First, 50% by weight of tetramethylolmethane tetraacrylate and 50% byweight of divinylbenzene were polymerized by suspension polymerization,and after that fine particles having a mean particle diameter of 7.01 μm(standard deviation 0.25 μm) were selected by the classification. TheK-value of the fine particles at 10% compression deformation was 468kgf/mm² and the recovery factor after the compression deformation in thecase of the maximum load value of 1 grf was 52%.

The resin fine particles were subjected to electroless nickel plating,after which conductive fine particles on which nickel-gold plated layerswere formed were obtained by the gold substitution reaction. Theanalysis of the conductive fine particles showed that gold content andnickel content were 30.5% by weight and 19.5% by weight, respectively.The mean particle diameter was 7.25 μm (standard deviation 0.29 μm).

A test chip was obtained in the same way as in Example 13 except thatthe above conductive fine particles were used. The reliability of thistest chip was tested. The results are shown in Table 1. From theresults, it was found that the contact reliability of the conductivefine particles was excellent.

Example 16

First, 25% by weight of tetramethylolmethane tetraacrylate and 75% byweight of divinylbenzene were polymerized by suspension polymerization,and after that fine particles having a mean particle diameter of 7.03 μm(standard deviation 0.28 μm) were selected by the classification. TheK-value of the fine particles at 10% compression deformation was 448kgf/mm² and the recovery factor after the compression deformation in thecase of the maximum load value of 1 grf was 52%.

The resin fine particles were subjected to electroless nickel plating,after which conductive fine particles on which nickel-gold plated layerswere formed were obtained by the gold substitution reaction. Theanalysis of the conductive fine particles showed that gold content andnickel content were 27.6% by weight and 24.3% by weight, respectively.The mean particle diameter was 7.27 μm (standard deviation 0.29 μm).

A test chip was obtained in the same way as in Example 13 except thatthe above conductive fine particles were used. The reliability of thistest chip was tested. The results are shown in Table 1. From theresults, it was found that the contact reliability of the conductivefine particles was excellent.

Example 17

First, divinylbenzene was polymerized by suspension polymerization, andafter that fine particles having a mean particle diameter of 7.05 μm(standard deviation 0.29 μm) were selected by the classification. TheK-value of the fine particles a 10% compression deformation was 330kgf/mm² and the recovery factor after the compression deformation in thecase of the maximum load value of 1 grf was 38%.

The resin fine particles were subjected to electroless nickel plating,after which conductive fine particles on which nickel-gold plated layerswere formed were obtained by the gold substitution reaction. Theanalysis of the conductive fine particles showed that gold content andnickel content were 25.6% by weight and 18.3% by weight, respectively.The mean particle diameter was 7.30 μm (standard deviation 0.32 μm).

A test chip was obtained in the same way as in Example 13 except thatthe above conductive fine particles were used. The reliability of thistest chip was tested. The results are shown in Table 1. From theresults, it was found that the contact reliability of the conductivefine particles was excellent.

Comparative Example 13

Spacers made of benzoguanamine polymers and having a mean particlediameter of 6.98 μm (standard deviation 0.25 μm) were subjected toelectroless nickel plating, after which conductive fine particles onwhich nickel-gold plated layers were formed by the gold substitutionreaction were obtained. The analysis of the conductive fine particlesshowed that gold content and nickel content were 30.4% by weight and19.6% by weight, respectively. The mean particle diameter was 7.23 μm(standard deviation 0.27 μm). The K-value of the conductive fineparticles at 10% compression deformation was 690 kgf/mm² and therecovery factor after the compression deformation was 12%.

A test chip was obtained in the same way as in Example 13 except thatthe above conductive fine particles were used. The reliability of thistest chip was tested. The results are shown in Table 1. From theresults, it was found that the contact reliability of the conductivefine particles was poor.

Comparative Example 14

First, 30% by weight of triallyl isocyanurate and 70% by weight ofdiallyl phthalate were polymerized by suspension polymerization, andafter that fine particles having a mean particle diameter of 7.00 μm(standard deviation 0.28 μm) were selected by the classification. TheK-value of the fine particles at 10% compression deformation was 245kgf/mm² and the recovery factor after the compression deformation was12%.

The fine particles were subjected to electroless nickel plating, afterwhich conductive fine particles on which nickel-gold plated layers wereformed were obtained by the gold substitution reaction. The analysis ofthe conductive fine particles showed that gold content and nickelcontent were 29.3% by weight and 20.9% by weight, respectively. The meanparticle diameter was 7.23 μm (standard deviation 0.30 μm).

A test chip was obtained in the same way as in Example 13 except thatthe above conductive fine particles were used. The reliability of thistest chip was tested. The results are shown in Table 1. From theresults, it was found that the contact reliability of the conductivefine particles was poor.

Comparative Example 15

First, fine particles made of polystyrene and having a mean particlediameter of 6.98 μm (standard deviation 0.27 μ) were subjected toelectroless nickel plating, after which conductive fine particles onwhich nickel-gold plated layers were formed by the gold substitutionreaction were obtained. The analysis of the conductive fine particlesshowed that the gold content and nickel content were 32.2% by weight and18.3% by weight, respectively. The mean particle diameter was 7.23 μm(standard deviation 0.29 μm). The K-value of the conductive fineparticles at 10% compression deformation was 116 kgf/mm² and therecovery factor after the compression deformation was not measurable.

The test chip was obtained in the same way as in Example 13 except thatthe above conductive fine particles were used. The reliability of thistest chip was tested. The results are shown in Table 1. From theresults, it was found that the contact reliability of the conductivefine particles was poor.

Comparative Example 16

First, fine particles made of silicon dioxide having a mean particlediameter of 7.01 μm (standard deviation 0.19 μm) were obtained. TheK-value of the fine particles at 10% compression deformation was 5100kgf/mm² and the recovery factor of the fine particles after thecompression deformation was 85%.

The fine particles were subjected to electroless nickel plating, afterwhich conductive fine particles on which nickel-gold plated layers wereformed by the gold substitution reaction were obtained. The analysis ofthe conductive fine particles showed that the gold content and nickelcontent were 27.4% by weight and 19.6% by weight, respectively. The meanparticle diameter was 7.25 μm (standard deviation 0.20 μm).

A test chip was obtained in the same way as in Example 13 except thatthe above conductive fine particles were used. The reliability of thistest chip was tested. The results are shown in Table 1. From theresults, it was found that the contact reliability of the conductivefine particles was poor.

                                      TABLE 1                                     __________________________________________________________________________           Thermal shock test                                                                              Moisture proof test                                         Electric resistance                                                                    Electric resistance                                                                    Electric resistance                                                                    Electric resistance                                (Ω) before test                                                                  (Ω) after test                                                                   (Ω) before test                                                                  (Ω) after test                        __________________________________________________________________________    Example 13                                                                           1.3      1.4      1.5      1.7                                         Example 14                                                                           0.8      0.7      1.9      1.8                                         Example 15                                                                           1.1      1.1      1.3      1.1                                         Example 16                                                                           0.5      0.7      0.9      0.8                                         Example 17                                                                           0.7      0.8      0.8      0.7                                         Comparative                                                                          0.5      2.8      0.7      3.1                                         Example 13                                                                    Comparative                                                                          0.8      10.1     0.9      12.3                                        Example 14                                                                    Comparative                                                                          0.3      149.0    0.4      253.0                                       Example 15                                                                    Comparative                                                                          58.0     98.0     73.0     135.0                                       Example 16                                                                    __________________________________________________________________________

Example 18

First, tetramethylolmethane tetraacrylate was polymerized by suspensionpolymerization, after which fine particles having a mean particlediameter of 6.98 μm (standard deviation 0.23 μm) were selected by theclassification. The K-value of the fine particles at 10% compressiondeformation was 570 kgf/mm², and the recovery factor of the fineparticles after the compression deformation in the case of the maximumload value of 1 grf was 63%.

The resin fine particles were subjected to electroless copper plating,after which copper was replaced with indium by the substitutionreaction. The analysis of the conductive fine particles showed that theindium content was 23.4%.

Then, 1 g of the conductive fine particles and 0.5 g of glass fibers(diameter: 5.5 μm, average length: 27.5 μm) were mixed with 75 g ofepoxy resin (Trade name SE-4500, manufactured by Yoshikawa Kagaku KogyoCo., Ltd.) and 25 g of hardening agent to form paste. Next, as shown inFIG. 6, the paste 13 was coated to a predetermined thickness on a glasselectrode 12 comprising an ITO film on an inner surface thereof, andanother ITO electrode 14 was superimposed. This lamination wassandwiched by a press machine and heat pressed at 35 kg/cm² and 160° C.for 30 minutes.

A test chip C so produced was tested through 240 cycles by using athermal shock testing apparatus (Trade name TSV-40, manufactured byTabai Espec Corp.) which operates at 90° C. for one hour and at -4° C.for one hour.

Another test chip produced in the same way as the above was put into athermo-hygrostat (Trade name PR-3F, manufactured by Tabai Espec Corp.)which operates under the conditions of 80° C. and 90% RH and tested for500 hours. The contact resistance between two electrodes were measuredbefore and after the thermal shock test and the moisture proof test byusing the four terminal method. The results are shown in Table 2. Fromthe results, it was found that the contact reliability of the conductivefine particles was excellent.

Example 19

First, 75% by weight of tetramethylolmethane tetraacrylate and 25% byweigh of divinylbenzene were polymerized by suspension polymerization,after which fine particles having a mean particle diameter of 7.05 μm(standard deviation 0.25 μm) were obtained. The K-value of the fineparticles at 10% compression deformation was 475 kgf/mm², and therecovery factor of the fine particles after the compression deformationin the case of the maximum load value of 1 grf was 55%.

The resin fine particles were subjected to electroless copper plating,after which the copper plated layer was subjected to the substitutionreaction to replace copper with indium. The analysis of resin fineparticles showed that the indium content was 19.8%.

A test chip was obtained in the same way as in Example 18 except thatthese conductive fine particles were used. The reliability of the testchip was tested. The results are shown in Table 2. From the results, itwas found that the contact reliability of the conductive fine particleswere excellent.

Example 20

First, 50% by weight of tetramethylolmethane tetraacrylate and 50% byweight of divinylbenzene were polymerized by suspension polymerization,after which fine particles having a mean particle diameter of 7.01 μm(standard deviation 0.25 μm) were obtained. The K-value of the fineparticles at 10% compression deformation was 422 kgf/mm², and therecovery factor of the fine particles after the compression deformationin the case of the maximum load value of 1 grf was 52%.

The resin fine particles were subjected to electroless copper plating,after which the copper layer so obtained was subjected to thesubstitution reaction to replace copper with indium. The analysis of theresin fine particles showed that the indium content was 20.3%.

A test chip was obtained in the same way as in Example 18 except thatthese conductive fine particles were used. The reliability of the testchip was tested. The results are shown in Table 2. From the results, itwas found that the contact reliability of the conductive fine particleswas excellent.

Example 21

First, tetramethylolmethane triacrylate was polymerized by suspensionpolymerization, after which fine particles having a mean particlediameter of 7.53 μm (standard deviation 0.28 μm) were obtained. TheK-value of the fine particles at 10% compression deformation was 282kgf/mm², and the recovery factor of the fine particles after thecompression deformation in the case of the maximum load value of 1 grfwas 58%.

The resin fine particles were subjected to electroless copper plating,after which the copper plated layer so obtained was subjected to thesubstitution reaction to replace copper with indium. The analysis of theresin fine particles showed that the indium content was 19.6%.

A test chip was obtained in the same way as in Example 18 except thatthese conductive fine particles were used. The reliability of the testchip was tested. The results are shown in Table 2. From the results, itwas found that the contact reliability of the conductive fine particleswas excellent.

Comparative Example 17

First, fine particles made of benzoguanamine polymers and having a meanparticle diameter of 6.98 μm (standard deviation 0.25 μm) were obtained.The K-value of the fine particles at 10% compression deformation was 620kgf/mm², and the recovery factor after the compression deformation inthe case of the maximum load value of 1 grf was 12%. The fine particleswere subjected to electroless copper plating, after which the copperplated layer so obtained was subjected to the substitution reaction toreplace copper with indium. The analysis of the fine particles showedthat the indium content was 22.6%.

A test chip was obtained in the same way as in Example 18 except thatthese above conductive fine particles were used. The reliability of thetest chip was tested. The results are shown in Table 2. From theresults, it was found that the contact reliability of the conductivefine particles was poor.

Comparative Example 18

First, fine particles made of silicon dioxide and having a mean particlediameter of 7.01 μm (standard deviation 0.19 μm) were obtained. TheK-value of the fine particles at 10% compression deformation was 4590kgf/mm². The recovery factor of the fine particles after the compressiondeformation was 85%.

The fine particles were subjected to electroless copper plating, afterwhich the copper plated layer so obtained was subjected to thesubstitution reaction to replace copper with indium. The analysis of thefine particles showed that the indium content was 9.8% by weight.

A test chip was obtained in the same way as in Example 18 except thatthe above conductive fine particles were used. The reliability of thetest chip was tested. The result are shown in Table 2. From the results,it was found that the contact reliability of the conductive fineparticles was poor.

                                      TABLE 2                                     __________________________________________________________________________           Thermal shock test                                                                              Moisture proof test                                         Electric resistance                                                                    Electric resistance                                                                    Electric resistance                                                                    Electric resistance                                (Ω) before test                                                                  (Ω) after test                                                                   (Ω) before test                                                                  (Ω) after test                        __________________________________________________________________________    Example 18                                                                           3.2      3.4      3.1      3.3                                         Example 19                                                                           2.8      2.7      3.0      2.8                                         Example 20                                                                           2.5      2.4      2.6      2.7                                         Example 21                                                                           1.8      1.9      2.0      1.9                                         Comparative                                                                          5.3      20.5     5.4      17.2                                        Example 17                                                                    Comparative                                                                          4.7      83.5     5.3      22.3                                        Example 18                                                                    __________________________________________________________________________

We claim:
 1. A fine sphere having: a K-value defined as ##EQU4##(wherein F and S represent a load value (kgf) and a compressiondisplacement (mm) at 10% compression deformation of said fine sphere,respectively, and R represents a radius (mm) of said fine sphere) whichis in the range of 250 kgf/mm² to 700 kgf/mm² at 20° C.; and a recoveryfactor after the compression deformation which is in the range of 30% to80% at 20° C.,wherein said fine sphere is made ofdivinylbenzene-tetramethylolmethane tetraacrylate copolymer.
 2. A finesphere according to claim 1, wherein said K-value is in the range of 350kgf/mm² to 550 kgf/mm².
 3. A fine sphere according to claim 1, whereinsaid recovery factor after the compression deformation is in the rangeof 40% to 70% at 20° C.
 4. A fine sphere according to claim 1, whereinsaid fine sphere has a diameter in the range of 0.1 to 100 μm.
 5. A finesphere according to claim 4, wherein the diameter of said fine sphere isin the range of 0.5 to 50 μm.
 6. A fine sphere according to claim 5,wherein the diameter of said fine sphere is in the range of 1.0 to 20μm.
 7. A fine sphere according to claim 1 further comprising aconductive layer formed on a surface of said fine sphere.
 8. A finesphere according to claim 7, wherein said conductive layer is anindium-plated layer.
 9. A spherical spacer for a liquid crystal displayelement having: a K-value defined as ##EQU5## (wherein F and S representa load value (kgf) and a compression displacement (mm) at 10%compression deformation of said spherical spacer, respectively, and Rrepresents a radius (mm) of said spherical spacer) which is in the rangeof 250 kgf/mm² to 700 kgf/mm² at 20° C.; and a recovery factor after thecompression deformation which is in the range of 30% to 80% at 20°C.,wherein said fine sphere is made ofdivinylbenzene-tetramethylolmethane tetraacrylate copolymer.
 10. Acolored spherical spacer for a liquid crystal display element comprisinga colored core fine sphere, said colored spherical spacer having: aK-value defined as ##EQU6## (wherein F and S represent a load value(kgf) and a compression displacement (mm) at 10% compression deformationof said colored spherical spacer, respectively, and R represents aradius (mm) of said colored spherical spacer) which is in the range of250 kgf/mm² to 700 kgf/mm² at 20° C.; and a recovery factor after thecompression deformation which is in the range of 30% to 80% at 20°C.,wherein said fine sphere is made ofdivinylbenzene-tetramethylolmethane tetraacrylate copolymer.
 11. Anadhesive coated spherical spacer for a liquid crystal display elementcomprising a core fine sphere and an adhesive layer formed on a surfaceof said core fine sphere, said adhesive coated spherical spacer having:a K-value defined as ##EQU7## (wherein F and S represent a load value(kgf) and a compression displacement (mm) at 10% compression deformationof said adhesive coated spherical spacer, respectively, and R representsa radius (mm) of said adhesive coated spherical spacer) which is in therange of 250 kgf/mm² to 700 kgf/mm² at 20° C.; and a recovery factorafter the compression deformation which is in the range of 30% to 80% at20° C.,wherein said fine sphere is made ofdivinylbenzene-tetramethylolmethane tetraacrylate copolymer.
 12. Aliquid crystal display element comprising a spherical spacer, saidspherical spacer having: a K-value defined as ##EQU8## (wherein F and Srepresent a load value (kgf) and a compression displacement (mm) at 10%compression deformation of said spherical spacer, respectively, and Rrepresents a radius (mm) of said spherical spacer) which is in the rangeof 250 kgf/mm² to 700 kgf/mm² at 20° C.; and a recovery factor after thecompression deformation which is in the range of 30% to 80% at 20°C.,wherein said fine sphere is made ofdivinylbenzene-tetramethylolmethane tetraacrylate copolymer.
 13. Aliquid crystal display element comprising a colored spherical spacercomprising a colored core fine sphere, said colored spherical spacerhaving: a K-value defined as ##EQU9## (wherein F and S represent a loadvalue (kgf) and a compression displacement (mm) at 10% compressiondeformation of said colored spherical spacer, respectively, and Rrepresents a radius (mm) of said colored spherical spacer) which is inthe range of 250 kgf/mm² to 700 kgf/mm² at 20° C.; and a recovery factorafter the compression deformation which is in the range of 30% to 80% at20° C.,wherein said fine sphere is made ofdivinylbenzene-tetramethylolmethane tetraacrylate copolymer.
 14. Aliquid crystal display element comprising an adhesive coated sphericalspacer comprising a core fine sphere and an adhesive layer formed on asurface of said core fine sphere, said adhesive coated spherical spacerhaving: a K-value defined as ##EQU10## (wherein F and S represent a loadvalue (kgf) and a compression displacement (mm) at 10% compressiondeformation of said adhesive coated spherical spacer, respectively, andR represents a radius (mm) of said adhesive coated spherical spacer)which is in the range of 250 kgf/mm² to 700 kgf/mm² at 20° C.; and arecovery factor after the compression deformation which is in the rangeof 30% to 80% at 20° C.,wherein said fine sphere is made ofdivinylbenzene-tetramethylolmethane tetraacrylate copolymer.